Key Considerations for Efficient Conveyor Chute Design
Head Chute Design
The dimensions of the head (discharge) chute around the discharge pulley are primarily determined by the conveyor's layout, accessibility for maintenance, and the initial trajectory of the material.
The diameter and face width of the head pulley play a crucial role in defining the width and height of the head chute. It's important to maintain a narrow gap between the chute wall and the pulley rim (typically 50 to 75 millimeters or 2 to 3 inches) to prevent large lumps from passing between the carrying side and the return side or getting stuck. This gap should allow for maintenance of the pulley and pulley lagging, as well as access to shaft bushings.
The head chute should ideally commence at the last full transition idler on the delivering conveyor. This positioning helps to contain any fugitive material that might otherwise fall from the belt during the transition from troughed to flat on the head pulley. Controlling the inlet area of the head chute is critical; dust curtains on the carrying sides and barrier seals on the belt return side are recommended to regulate airflow and minimize material spillage.
Drop Chute Design
After the material's direction is altered by contact with the head chute, it typically flows into drop (transition) chutes. These drop chutes often extend with duct-like structures to align the material stream properly with the receiving conveyor.
Drop chutes must be sufficiently steep to prevent bulk material from adhering to the walls and large enough to prevent blockages. Design guidelines suggest that the cross-sectional area of a drop chute should be at least four times the cross-sectional area of the material profile. Additionally, the width and depth of drop chutes should be at least 2.5 times the size of the largest lump expected to pass through. Designers frequently adjust these ratios based on their experience with specific materials, sometimes reducing them for uniform, free-flowing bulk materials tailored to the chute's specific engineering properties.
Loading Chute Considerations
The width of the loading (receiving) chute should be carefully designed to maintain the minimum belt edge necessary for effective sealing and to accommodate potential belt mistracking.
One common pitfall in chute design is creating overly abrupt transitions between drop chutes and loading chutes. This can lead to chutewall angles that promote material buildup and subsequent blockages. Modern design practices recommend using valley angles of at least 60 degrees, with 75 degrees being preferred, to mitigate these issues.